polio

Polio in the Syrian Arab Republic

Tuesday, 29 October 2013

The Syrian Arab Republic, polio-free since 1999, have confirmed cases of wild poliovirus.

The World Health Organization (WHO) have reported a cluster of 22 cases of acute flaccid paralysis with laboratory investigation of 10 of these cases identifying wild poliovirus type 1. Most of the cases are children under two years of age who were unimmunised or had not completed their primary course of polio immunisations.  The WHO identifies the risk of international spread of wild poliovirus across the region as high.

Link to the WHO Global Alert and Response webpage for more information.

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IPOL

IPV

IPOL is used for primary and booster vaccination of infants, children and adults to protect against infection with Type 1, Type 2 and Type 3 polioviruses causing poliomyelitis.

Infanrix®-IPV

DTaP-IPV

Infanrix®-IPV is used for primary and booster vaccination of infants and children up to their 7th birthday to protect against diphtheria, tetanus, pertussis and poliomyelitis.

Infanrix®-hexa

DTaP-IPV-HepB/Hib

Infanrix®-hexa is used for primary and booster vaccination of infants and children up to their 5th birthday to protect against diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis and disease caused by Haemophilus influenzae type b.

 

Poliomyelitis

Common Name: 
Polio
Parents & Caregivers
Introduction: 

Poliomyelitis is a highly contagious viral disease caused by three types of poliovirus (types 1, 2 and 3).  Prior to the development of polio vaccines nearly every person became infected, with the highest disease rate being in infants and young children. Infection can result in irreversible paralysis, usually of the leg muscles but for 5-10% of acute flaccid paralysis cases the breathing muscles are paralysed and the person may die.

The World Health Organization is a partner in the Global Polio Eradication Initiative with Rotary International, the United States Centers for Disease Control and Prevention and UNICEF.  The goal of the Initiative is to reach every last child with polio vaccine and ensure a polio-free world for future generations. Since 1988 polio case numbers have reduced by 99%.

There are just four countries in the world that have (endemic) polio Afghanistan, India, Nigeria and Pakistan. Polio can travel from these four countries to any other “polio free” country in the world and infect people who have not had the disease or been immunised. In 2009-2010, 23 previously polio-free countries were re-infected due to imports of the virus.

Humans are the only host for polioviruses. Polio can be eradicated through immunisation. If every person is immune the polioviruses have no one to infect and will die out. Type 2 wild poliovirus was eradicated in 1999.

A brief history: 

Poliomyelitis was recorded on an Egyptian stele as far back as 1580-1350BC, in the image of a man with flaccid paralysis of a leg. It was described later by Michael Underwood in 1789. Epidemics and major outbreaks occurred over the 19th century.

A weakened (attenuated) live oral polio vaccine is used by the World Health Organization’s Expanded Programme on Immunization. There is a small risk that the weakened poliovirus in the vaccine can cause vaccine associated paralytic poliomyelitis (VAPP) in someone who is not immune to polio and is exposed to the vaccine virus.

An inactivated poliomyelitis vaccine, licensed for use in the US in the mid-90s, it is primarily used in countries that have eradicated polio. There is no risk of VAPP from the inactivated polio vaccine.
New Zealand started immunising against polio in 1961 using the oral polio vaccine. The inactivated polio vaccine was introduced in 2002 to reduce the risk of VAPP.

The current New Zealand situation: 

Until polio is eradicated worldwide there remains a risk of polio returning to “polio free countries”, including New Zealand.

Since 1962 there have been seven cases of polio reported in New Zealand, the most recent was in 1998. Four cases were laboratory confirmed as vaccine associated and two were classified as probably vaccine related, before New Zealand changed from the oral polio vaccine to the inactviated polio vaccine in 2002. One case was wild polio (not vaccine related), acquired in Tonga and imported into New Zealand.

Symptoms: 

The majority of cases (approximately 95 in 100) have no symptoms.

  • Between 4-8 in 100 cases have symptoms of a minor non-specific illness including a low grade fever, fatigue, headache, vomiting, neck stiffness, sore throat and/or muscle pain.
  • In about 1-5 in 100 cases the person develops aseptic meningitis a few days after they have recovered from their non-specific illness. They usually recover fully.
  • Up to 2 in 100 cases have a rapid onset of acute flaccid paralysis without normal reflexes in the affected areas.
How do you get it?: 

Humans are the only host for polioviruses. People infected with a poliovirus excrete the virus in their saliva and faeces whether they have symptoms of the disease or not. Poor hygiene then spreads the virus to others.

Polioviruses are passed from person-to-person through the oral-faecal or oral-oral route. Occasionally the viruses may be passed on through contaminated water, milk or food.

The incubation period is usually 3-6 days in a person with no symptoms or for a person to develop non-specific symptoms.  The incubation period between exposure and development of paralytic disease is usually 7-21 days but could be as short as 3 days or as long as 35 days.

What are the risks?: 

Most people fully recover from polio.

The complications from polio depend on what part or parts of the body have been affected by the poliovirus.
People may experience permanent muscle weakness or paralysis, difficulty passing urine and urinary tract infections, uneven limb growth (the affected leg does not grow and the unaffected leg continues to grow normally), bone deformities, heart problems, breathing problems, cranial nerve damage, brain damage and death.

People who have had polio may experience significant muscle pain and weakness 15-40 years after recovering from polio. This is called post-polio syndrome. It is thought to be related to the aging of muscles and nerves that are compensating for the original damage. The person does not have the disease again.

Who is most at risk?: 

In countries where polio remains endemic infection is more common in children less than 5 years of age. When most children have acquired protection against all three types of polio by 5 years of age and therefore are protected as they grow into adulthood the risk of acute flaccid paralysis is highest in children less than 3 years of age.

In countries that are polio free people who have not had polio or been immunised against polio are at risk of getting polio when it is imported/introduced into the country b y a traveller. In this situation adults are more likely to develop acute flaccid paralysis than children. In 1993 the Netherlands experienced a polio outbreak in a community who had chosen not to immunise against polio.

Treating the symptoms: 

Polio is incurable.

During the acute illness only supportive care can be provided to reduce complications associated with paralysis.

After the person has recovered rehabilitation can prevent or reduce post-polio deformities and increase independence.

Preventing Disease Spread: 

Polio can only be prevented through immunisation.

Household contacts of a person with polio are usually infected before the polio has been diagnosed in the first case so isolation of the person with polio in the home environment after diagnosis is not useful.

Health Professionals
Causative organism: 

Polioviruses are enteroviruses and belong to the family Picornaviridae. There are three antigenic types (serotypes 1, 2 and 3).

Type 1 appears to be the most neurovirulent of the three serotypes. Most cases are caused by type 1. Type 2 was eradicted in 1999.

The viruses are resistant to inactivation by many common detergents and disinfectants, including soaps, non-ionic detergents and lipid solvents such as ethanol, ether, and chloroform. They are rapidly inactivated by 0.3% formaldehyde or 0.5 ppm free residual chlorine, by desiccation, low humidity or by exposure to ultraviolet light.

Clinical signs, symptoms and complications: 

The incubation period is usually 3-6 days in a person with no symptoms or for a person to develop non-specific symptoms. The incubation period between exposure and development of paralytic disease is usually 7-21 days but could be as short as 3 days or as long as 35 days.

After infection the poliovirus initially incubates in the gastrointestinal tract. Polio has four possible presentations:

1. The majority of poliovirus infections (about 95%) are subclinical, inapparent infection without symptoms.

2. About 4-8% of cases only develop a minor non-specific illness. Symptoms may include low grade fever, fatigue, malaise, drowsiness, headache, vomiting, constipation, neck stiffness, sore throat and/or muscle pain.

3. About 1-5% of cases are nonparalytic poliomyelitis. Initial symptoms are non-specific (fever, malaise, vomiting, sore throat). One to two days later symptoms of meningeal irritation from aseptic meningitis develop. Recovery is usually complete however nonparalytic poliomyelitis can progress to the paralytic form of the disease.

4. Between 0.1-2% of cases are paralytic poliomyelitis. The paralytic form of the disease occurs when the poliovirus spreads to the motor neurons of the anterior horn cells in the spinal cord (spinal poliomyelitis) and/or brain stem (bulbar paralysis). The cranial nerves may also be affected by polioviruses. The area paralysed depends on the anatomic location of the motor neuron damage. Although the motor neurons do not recover and are not replaced it is possible for other muscles to compensate for the paralysis, resulting in partial or complete recovery from paralytic poliomyelitis for some people.

In polio-free countries with pockets of non-immune/unimmunised communities adults are more likely to present with paralytic poliomyelitis. In countries with endemic polio children less than 3 years are more likely to develop paralytic polio.

The person initially experiences symptoms of a minor non-specific illness, becomes symptom free, then one to three day later develops fever with a rapid onset of descending acute flaccid paralysis. Adolescents and adults may not experience the minor illness symptoms but develop more severe pain in the affected extremities. The progression of paralysis usually stops once the fever abates. Paralysis is usually asymmetrical with reduced or absent deep tendon reflexes. The sensory nerves are not affected.
The diagnosis of paralytic poliomyelitis is based on the clinical course, isolation of poliovirus in two stool samples and the presence of a neurologic deficit 60 days after symptom onset. Neurologic deficit may be complete or partial flaccid paralysis or weakness.
The two stool samples must be taken at least 24 hours apart in the first 14 days after the onset of paralysis are required to diagnose paralytic poliomyelitis. The laboratory must be notified before sending the specimen. Isolation of the virus in stool samples is important to determine if the virus is wild-type or vaccine related.

The differential diagnoses for acute flaccid paralysis include infection by other enteroviruses, other viruses (e.g., Epstein-Barr virus, human immunodeficiency virus, mumps virus), campylobacter jejuni, hypokalaemia, antibiotic reaction (aminoglycosides, tetracyclines, polymixin B), chemical poisoning, cephalic tetanus, fungal-mycotoxins, wasp venom, Guillain-Barre Syndrome, Bell’s Palsy, transverse myelitis.

The complications from polio depend on the anatomic location of the motor neuron damage. People may experience permanent muscle weakness or paralysis, difficulty passing urine and urinary tract infections, uneven limb growth (the affected leg does not grow and the unaffected leg continues to grow normally), bone deformities, heart problems, breathing problems, cranial nerve damage, brain damage and death.

The fatality rate from poliomyelitis varies depending on the presentation. For paralytic spinal poliomyelitis 2-5% of child cases and 15-30% of adult cases may result in death. Up to 75% of cases with bulbar poliomyelitis will die.
People who are immunocompromised are more likely to experience complications and a fatal outcome from poliomyelitis.

Post-polio syndrome occurs 15-40 years after a person has recovered from paralytic poliomyelitis. It is characterised by exacerbation of existing weakness, development of new weakness or paralysis and/or increased muscle pain. Increasing length of time since the acute infection, presence of residual impairment form the acute illness and being female are risk factors for post-polio syndrome. The pathogenesis of post-polio syndrome does not involve ongoing or recurrent poliovirus infection. It is thought to be related to the aging of muscles and nerves that are compensating for the original damage.

Method of transmission: 

Humans are the only host for polioviruses.

Polioviruses are transmitted person to person via the oral-faecal or oral-oral route. They have occasionally been transmitted through contaminated water, milk or food.
All infected people shed the virus in their stool, including those with subclinical/inapparent infection.
The person is most infectious immediately before to 1-2 weeks after the onset of symptoms. However the virus is excreted in saliva for approximately two weeks and in faeces for three to six weeks and sometimes longer.

People who are immunocompromised may excrete the virus for years (chronic excretor).

Public health significance: 

All cases of acute flaccid paralysis in New Zealand must be investigated as suspected poliomyelitis and notified to the Medical Officer of Health immediately.

Acute flaccid paralysis in persons aged less than 15 years should also be reported to the New Zealand Paediatric Surveillance Unit (NZPSU) based at the University of Otago. The NZPSU will send case investigation and follow up forms to clinicians, continue to monitor that New Zealand has eradicated polio and provide information to the World Health Organization.

Any confirmed case of poliomyelitis in New Zealand constitutes a Public Health Emergency of International Concern (PHEIC). The Director of Public Health at the Ministry of Health should be contacted urgently. The New Zealand National Poliomyelitis Response Plan outlines the actual response and is published on the Ministry of Health website. (http://www.health.govt.nz).

The infection rate of non-immune household or institutional contacts is as high as 90-100%.
Both a live oral polio vaccine (OPV) and an inactive polio vaccine (IPV) are effective at preventing disease from polioviruses because inhibition of poliovirus replication in and dissemination from the gastrointestinal tract (OPV) and/or inhibiting viraemia (IPV) following infection prevents disease.

As humans are the only host polioviruses can be eradicated through immunisation. In developed countries with high sanitation and hygiene standards immunisation coverage of 66-80% can prevent outbreaks of polio. In developing countries with lower sanitation and hygiene standards immunisation coverage needs to be much higher with 94-97% of the population having completed a primary course of three doses of polio vaccine.

Until polio is eradicated worldwide there remains a risk of polio returning to “polio free countries”, including New Zealand.

New Zealand epidemiology: 

Polio became a notifiable disease in New Zealand in 1908. Since then epidemics (about 1000 cases) were recorded in 1916, 1925, 1937, 1948/49, 1952/53 and 1955/56. Use of the Salk inactivated polio vaccine began in 1956 for older children and extended to all those aged 6 months to 29 years in 1956. The use of this vaccine delayed the next polio epidemic to 1961.

The Sabin oral vaccine was introduced to New Zealand in 1961 for children less than 12 months of age. Its use was extended to school aged children, and all adolescents and adults in 1962. There have not been any cases of locally acquired wild-type polio in New Zealand since 1962.

Since 1962 there have been seven cases of polio reported in New Zealand, the most recent was in 1998. Four cases were laboratory confirmed as vaccine associated (two vaccine recipients and two unimmunised contacts of vaccine recipients). Two were classified as probably vaccine related. In 1976 an infant was diagnosed with wild-type polio acquired in Tonga and imported into New Zealand.

New Zealand changed from using the live oral polio vaccine to the inactivated injectable polio vaccines in 2002.

Until polio is eradicated worldwide there remains a risk of polio returning to “polio free countries”, including New Zealand.

Prevention: 

High standards of public sanitation and hygiene will contribute to reducing the spread of poliovirus.

Immunisation is the only way to prevent the disease.

The inactivated polio vaccine (IPV) is used in New Zealand to provide individual protection and herd immunity against polio without the risk of vaccine associated paralytic poliomyelitis (VAPP) that is associated with use of the live oral polio vaccine. IPV can also be safely administered to people who are immunocompromised and close contacts of people who are immunocompromised.

A combination of oral and inactive injected polio vaccines are acceptable to provide a primary course and booster dose of polio vaccines.

Occupational vaccination and travel:
There is no evidence that routine IPV boosters are required however they are currently recommended to reduce any possible risk form waning immunity when there is an increased risk of exposure to poliovirus.

If more than 10 years has elapsed since completing a primary course of three polio containing vaccines or polio containing booster vaccine a booster dose of IPV is recommended (but not funded) for:

  • Travellers to countries where poliomyelitis remains endemic.
  • Individuals at particular risk of exposure (e.g., sewerage workers, laboratory workers routinely handling faecal specimens which may contain wild or vaccine-derived polioviruses).
  • Healthcare workers in direct contact with a case of poliomyelitis.
Treatment: 

Polio is incurable.

During the acute illness only supportive care can be provided to reduce complications associated with paralysis.

After the person has recovered physical rehabilitation can prevent or reduce post-polio deformities and increase independence.

 

Disease Effects vs Vaccine Side Effects (Table)
Disease Description: 

Poliomyelitis is a highly contagious viral disease caused by three types of poliovirus (types 1, 2 and 3).

 

 

 

Effects of disease: 
The majority of cases (approximately 95 in 100) have no symptoms.
Between 4-8 in 100 cases have symptoms of a minor non-specific illness including a low grade fever, fatigue, headache, vomiting, neck stiffness, sore throat and/or muscle pain.
In about 1-5 in 100 cases the person develops aseptic meningitis a few days after they have recovered from their non-specific illness.
The majority of people fully recover from polio.
Up to 2 in 100 cases have a rapid onset of acute flaccid paralysis without normal reflexes in the affected areas.
The complications from polio depend on what part or parts of the body have been affected by the poliovirus.
People may experience permanent muscle weakness or paralysis, difficulty passing urine and urinary tract infections, uneven limb growth (the affected leg does not grow and the unaffected leg continues to grow normally), bone deformities, heart problems, breathing problems, cranial nerve damage, brain damage and death.
People who have had polio may experience significant muscle pain and weakness 15-40 years after recovering from polio. This is called post-polio syndrome.
Common side effects of vaccine: 
Soreness/pain, redness and/or swelling around the injection site.
Fever over 38°C.
Decreased appetite, vomiting and/or diarrhoea.
Irritability, restlessness.
Unusual crying.
Fatigue.
Uncommon side effects of vaccine: 
Fever over 39.5°C.
Induration (area of hard inflammation).
Swelling involving the entire thigh or upper arm occurs in 2–3 percent of children after administration of the fourth and fifth doses of acellular pertussis vaccine. It resolves spontaneously without long term consequences.
Rare/very rare side effects of vaccine: 
Anaphylaxis.
Urticaria.
Idiopathic thrombocytopenic purpura.
Persistent (> 3 hours) inconsolable screaming.
Hypotonic, hyporesponsive episode (HHE) with 24 hours of immunisation.
Convulsion within 2 days of immunisation.
Inflammation of the nerve in the arm causing muscle weakness and pain (brachial neuritis) occurs within four weeks of immunisation, 1- 2 times per 200,000 doses
Encephalopathy less than once in one million doses.

What if a child has already had four doses of polio vaccine?

Answer: 

In New Zealand the inactivated polio vaccine is usually administered in a three-dose series in the first year of life, followed by a booster dose around school entry age as part of the Infanrix®-IPV (DTaP-IPV) vaccine. A child having already had four polio vaccines is an uncommon situation but may occur for children vaccinated under an overseas schedule. 

It is safe to administer a fifth dose of polio vaccine.

Boostrix® (Tdap) is available for private purchase. It does not have a polio component however when administered to children less than 10 years of age it must be prescribed by a Doctor outside of its license.

FAQ types: 
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